Ideas & Trends; Snooping's Not Just For Spies Any More

NOT so long ago, it seems, nations were able to hide their armaments, misdeeds and fortresses from the eyes of nosy civilians, while militaries could pry into most corners of the globe from spy satellites, knowing they could control who could take a peek.

No more. Taking pictures from space is undergoing a revolution, and it is making some governments feel naked.

Private companies in a growing number of countries are launching an increasingly sophisticated fleet of reconnaissance satellites, and governments are finding it harder and harder to restrict what snapshots are distributed to anyone willing to pay.

A recent case involves Area 51, a secret military installation in a secluded valley northwest of Las Vegas that is thought to be used to test advanced aircraft. For decades, the American government kept it off limits to cameras. Known officially as Groom Lake, it was veiled in high security, mysterious lights and, U.F.O. buffs claim, test flights of captured alien spaceships.

Last week, private sleuths won a quiet battle for openness at Area 51 -- at least on what can be seen from the sky -- as commercial rivals sold space photos of it. In the fast developing field of private photography from orbit, the episode suggests a new frailty for any efforts at state censorship.

When civilian reconnaissance craft were first launched into space in 1972, there was a vast technological gap between them and their older but more powerful cousins, the military spy satellites. All the civilian photos of small objects in those days were fuzzy. But over the decades, they have become increasingly sharp. At first, the spacecraft were able to show identifiable objects no smaller than 100 meters ( 300 feet). Then that number fell to 30, 10, 5, 2 and now 1 meter, or 3 feet. At that resolution, cars, roads, buildings, tanks, ships, jets and missiles can be distinguished.

So far, only one company, Space Imaging, in Thornton, Colo., has put a one-meter craft into orbit. But other companies in the United States, Russia, Japan, Israel and South Korea are planning to follow suit.

Already, analysts say, commercial spy craft are so numerous and competitive as to undercut governmental efforts to curb what they disseminate. Russia can bar the operators of a Russian satellite from selling pictures of Chechnya, but it has no power over an American company. Likewise, any American efforts to control spying on Area 51 were rendered moot last week when a Russian company put its imagery of the base on the market. Some snoop, the experts say, will always be willing to sell closeups of sensitive zones that some other nation wants off limits, encouraging a free-for-all.

''It won't last,'' Ann M. Florini, a space reconnaissance expert at the Carnegie Endowment in Washington, said of state censorship. ''It's hard to imagine any foreign-policy situations where all the actors are going to get together and agree, 'Yes, that imagery is not going to be disseminated.' ''

In military terms, of course, it's been decades since any nation could count on real security from the prying eyes of foes. Missile testing, bomb development and large-scale military operations have long been detected -- or forced to try to hide from spy satellites by dint of camouflage and subterfuge. Even so, it hasn't usually been to the spyer's advantage to make its discoveries public, since a cardinal rule of espionage is to keep your discoveries to yourself. And that, in a way, made the game all the more secretive and manageable.

But commercial companies don't play by those rules. What is new is the prospect that any country's secrets will come unpredictably under public display in ways that could embarrass governments, tip their hands in war and debate, or show sensitive installations to terrorists or just plain mischief-makers. Imagine if the F.B.I.'s and K.G.B.'s eavesdropping gear suddenly fell into the hands of voyeurs, and you get a hint of the queasiness now felt in high places.

For a time, even after cameras started zooming, states could exert some control over civil reconnaissance from space. In 1995, India lofted a craft that took five-meter images. It photographed the world, but blocked photos of its own military bases. And in 1996, after the Clinton Administration approved the taking of one-meter photos, American supporters of Israel won a law limiting the sharpness of images of Israel to the best obtainable by any foreign company. Today, that means two-meter sharpness, which a Russian company sells.

IN the United States, the investigative use of space imagery has been strongly encouraged by the Public Eye program of the Federation of American Scientists, a private group in Washington that promotes arms control and has bought satellite photos in a systematic effort to fight military censors. In January, it revealed a North Korean missile base, and in March a Pakistani nuclear reactor and missile site.

Its newest target is Area 51, and it played a big role in the release of the new imagery.

Public Eye ordered Area 51 photos from Space Imaging last winter -- to no avail, leaving it wondering whether there had been what experts call ''shutter control,'' a right that American officials assert to at times restrict American-owned civil spy cameras, or self-censorship by Space Imaging, which is owned mainly by Lockheed Martin, a military contractor, and whose largest customer is the Pentagon. The company denied there had been either.

The logjam broke Monday when a rival American company, Aerial Images, based in Raleigh, N.C., released Russian two-meter photos of the secretive base.